\documentclass{article}
\usepackage{amssymb,amsmath,amscd,concmath}
\pagestyle{empty}
\begin{document}
\begin{equation*}
S= \{(Texas,Florida) \in \mathbb{R}^2:a \leq x \leq b ,0 \leq y \leq f(x)\}, 
\end{equation*}
\end{document}
